Stabilized tracking and fire control system



Dec. 1, 1953 c. G. HOLSCHUH ETAL 2,660,793

STABILIZED TRACKING AND FIRE CONTROL SYSTEM Filed May 22, 1942 7 Sheet s-Sheet 1 Q 7 I 1., I 507 69 5l"7 A H TRANS.

Remofe Conirol TRACKING 42 CONTROL lll INVENTORS,

OGHOLSCHUH, [.B. HAMMOND and W. WHITE- Dec. 1, 1953 c. G. HOLSCHUH E'TAL 2,660,793

STABILIZED TRACKING AND FIRE CONTROL SYSTEM Filed May 22, 1942 7 Sheets-Sheet 2 L 13 SIGNAL J I AMPLIFIER INVENTORS C.G HOLSCHUH EB. HAMMOND I d l BY an .T.WH|T :07 2 M THEIR ATTORNE Dec. 1, 1953 c. G. HOLSCHUH ETAL 2,660,793

STABILIZED TRACKING AND FIRE CONTROL SYSTEM Filed May 22, 1942 '7 Sheets-Sheet 4 l3 s To Guns A TR.

; RANGE SE RVO Signal EiErY...

NVENTORS,

l C.G.HOLSCHUH, EBHAMMOND r.

W.T. HITE THEI ATTORNEY- Dec. 1, 1953 c. G. HOLSCHUH ET AL 2,660,793

STABILIZED TRACKING AND FIRE CONTROL SYSTEM Filed May 22, 1942 7 Sheets-Sheet 5 Remoe Siqhf 224 Ramon Signal- SIG- GEN AM PLIFI I34 To Guns COMPUTING Ag MECHANISM INVENTORS TRACKING C.G.HOLSCH UH, E B HAMMOND n, l7 CONTROL and W.T.WH|TE;

THEIR ATTORNE.

7 Sheets-Sheet 6 mvam-ons, C.G.HOLSCHUH, E.B.HAMMOND ]r-,

and T.WH|TE M THEIR ATTORNE Dec. 1, 1953 c. G. HOLSCHUH ET AL STABILIZED TRACKING AND FIRE CONTROL SYSTEM Filed May 22, 1942 D. h 4 v\ V s 4 I 3 2 I mw I E mm R1? L E M gm 1 m Q I f 'MIHI- w 3w: M 2 I m m Patented Dec. 1, 1953 UNITED STATES STABILIZED TRACKING AND FIRE CONTROL SYSTEM corporation of Delaware Application May 22, 1942, Serial No. 4.44am

2% Claims.

The present invention is concerned with fire control apparatus especially adapted for aircraft use.

In prior systems, such as shown in abandoned application Serial No. 411,186, for Aircraft Gun- Sight and Computer, filed September 17, 1941, in the names of C, G. Holsohuh and D. Fram; and application Serial No. 424,612 for Hydraulic Remote Operating Systems, filed December 27, 1941, in the names of E. L. Dawson, 15. M. Watkins and C. N. Schuh, Jr., now Patent No. 2,445,765, known interaircraft fire control sys tems comprise an optical sighting device, a computing mechanism, and remotely controlled gun turrets. The sighting device is manually actuated by the fire control officer to track with a target, and thereby present target position data and present target rate data are set into the computing mechanism. From these input data, the computing mechanism then determines the correct gun aiming angles for properly orienting the guns to intercept the target by a projectile at the target future position. The data determined by the computer then serve to automatically orient the gun turrets to the correct positions. In such prior systems, the controls for the computing mechanism and sighting devices are usually such that a displacement of the manual control produces a corresponding velocity of the sighting device, with an additional proportional component of displacement of the sighting device superimposed thereupon, such control being known as aided tracking. The target orientation data for the computer are determined from the orientation of the sigh ing device, which, during the proper tracking condition, corresponds exactly to the target orientation. The target rate data required by the computing mechanism are derived from the displacement of the manual control, which is proportional thereto.

Such fire control systems on aircraft have been found to be highly satisfactory under smooth flying conditions and with good visibility conditions. However, the effective use of such a system is seriously impaired during poor flying conditions or during maneuvers of the craft in which the erratic motion of the craft carrying the sighting device creates great difficulty in properly performing the required tracking operations. These difiiculties are overcome in the present system by the provision of proper stabilization, in which the motion of the sighting device produced by the manual control of the operator is referred to a reference which is fixed with respect to space rather than with respect to the craft, as in prior systems. This stabilization is added without affecting the meth-v od of operation of the system. Such a stabilization may be. produced in several ways.

In, one. embodiment of the present invention, the elevation and azimuth components of the sighting device orientation and of the target orientation data input to the computing mechanism are independently stabilized by means of respective free gyroscopes which maintain their orientations fixed in space and hence effectively fixed with respect to the earth. Any change in orientation of the craft with respect to space, such as may be caused by rough air, vibration or oscillation of the craft, or by maneuvering of the craft, produce stabilization components which are introduced to control the sighting device and the corresponding data inputs to the computing mechanism. Therefore, in order to maintain the sighting device oriented toward the target, the fire. control ofiicer need merely compensate for the motion of the craft with respect to the reference positions defined by the gyroscopes, and, accordingly, his control remains unafiected by variations in attitude of the craft for any reason.

A second embodiment of the invention utilizes a single free gyroscope whose orientation, defined by its spin axis, is made to track with the orientation of the target by the application of suitable precessing torques applied to the respective gimbal axes of this gyro, Considering for the moment a target fixed with respect to space, it will be clear that no processing torques are necessary to maintain the gyro oriented toward this target and any variations in the attitude of the craft will have .no effect upon the orientation of the gyro, Since the gyro tends to maintain itself oriented in space. The same situation holds when the target is moving with respect to space, since then the only corrective effects which have to be applied to the gyro to maintain its orientation toward the target are those determined by motion of the target in space or the angular motion of the target relative to the gyro-defined axes, the changing attitude of the craft being completely ineffective in the system. The gyro orientation, being thus stabilized, is used to control the sight orientation and the computer data inp In addition to the provision of stabilization in the present invention, further improved apps ratus is provided for in roduc n the require rate data into the computing mechanism. Pref erably, the manual control operated by the fire control oiiicer is made of the rate type, that is, where the displacement of the control is proportional to the rat of change of the line of sight to be tracaed with the target, along the elevation and azimuth components. It will be clear that the rate data required may be obtained directly from the displacement of this manual control, at least in the first embodiment of the invention described above. In the second embodiment oi the invention described, the property of gyroscopes, whereby the angular velocity of precession of the spin axis is proportional to the applied torque, is utilized to supply the rate data input to the computing mechanism. Here the manipulation of the manual tracking control b the fire control officer produces a signal. preferably electrical in character, which is utilized to produce a proportional torque on the free gyro. Since the torque, and hence the signal, is thereby proportional to the rate of change of the orientation of the gyro, the signal may be utilized directly to correspondingly control the rate input to the computing mechanism. Alternati ely, suitable rate gyroscopes directly coupled to the sight and computer orientation controls may b used to derive the required computer rate data.

In order to overcome the difiiculties involving visibility conditions, recourse is had to a radiooperated system similar to that shown and described in copending application Serial No. 441,188 for Radio Gun Control Systems, filed April 30, 1942 in the names of C. G. I-Iolschuh, G. E. White, W. W. Mieher and J. Shepherd now Patent No. 2,817,982. As described in this prior application, a radio scanner is provided which, during tracking operations, is utilized either to indicate the relative displacement between the scanner orientation and the tar et orientation, or to automatically orient the scanner towards the target. In the present system, a similar scanning device is combined with the stabilization described above and the combined results and advantages of stabilization and radio vision are obtained, extending the usefulness of such fire control systems to conditions of poor visibility, increased ran e, and variable or erratic attitude )1 the craft which were hitherto not realizable.

Accordingly, it is an obiect of the present invention to provide improved fire control systems Jseful over an extended range of conditions with res ect to prior systems.

It is another object of the present invention to arovide improved stabilization devices for si htng devices and in particular for aircraft fire con- ;rol systems.

It is still another obiect of the present inven- ;ion to provide improved devices for producing aarget rate data and target orientation data for ice in computing gun sights.

It is a further obiect of the present invention provide improved radio-operated fire control :ystems for aircraft.

It is still a further object of the present invenion to provide improved radio-operated fire conrol systems for aircraft including stabilization.

Further objects and advantages of the present nvention will become apparent from the followng specification and drawings, in which Fig. 1 shows a schematic representation of one mbodiment of the present invention including he use of separate free gyros for stabilization.

Fig. 2 shows a schematic representation of the racking control of Fig. l.

Fig. 3 shows a diagrammatic representation of the elevation or azimuth servo of Fig. 1.

Fig. 4 shows a schematic perspective representation of an alternate form of elevation stabiiization device useful Fig. 1.

Fig. 5 shows a schematic perspective repre sentation of a remote sighting device useful with Fig. 1.

Fig. 6 shows a schematic representation of a modification of the system of Fig. in which rate gyros are used for producing the computing mechanism rate data.

Fig. '7 shows a schematic representation modified form of rate gyro which may be used in the system of Fig. 5.

Fig. 8 shows a schematic representation modi fled form of computer andsighting device system.

Fig, 9 shows a schematic representation of a further embodiment of the system of the present invention utilizing a free gyro for tracking pur poses, and

Figs. ldA and 1013, taken jointly, illustrate still another embodiment of the system of the invention utilizing a radio scanning device and the free tracking gyro of Fig. 9 with a remotely situated computing mechanism and tracking control.

Fig. 1 shows one embodiment of th invention adapted to provide an improved and stabilized control for inter-aircraft gun sights and computers, such as of the type shown in above-mew tioned copending application Serial No. 411,185.

In this copending application, a computing mechanism is described which is adapted to have set into it data corresponding to target dimension (T. 1).), indicated air speed (I. A. S.) of the craft, altitude (H) of the craft, the present posi tion of the target relative to the craft in terms of its elevation (E0), azimuth (A0) and slant range (Do) coordinates, and the rates of change of the azimuth and elevation coordinates (Ar, E1). and to produce from these data the proper gun elevation (Eg) and gun azimuth (Ag) data to determine or indicate the proper gun aiming angles whereby the guns may effectively fire at the future position of the target. A sighting devi cc. such as a telescope, defining a line of sight coupled to the present position data input so that the orientation of the sighting device corresponds to the data input to the computing mechanism. The orientation of the sighting device and the position data setting of the computing mechanism are manually controlled by the operator, who continuously maintains the orientation of the sighting device coincident with the target orientation, as evidenced by suitable reference marks or cross-hairs on the sighting device. When the sighting device is thus tracking with the target, the proper target position and rate data are provided for the computing mechanism.

In Fig. 1 such a computing mechanism is schematically indicated by the block. l, including its target dimension control 2, its indicated air speed control 3, and its altitude control i. The arrows placed beside various control shafts and on control wires indicates the direction or flow of control eifects. Present target elevation data may be set into the computing mechanism I as by shaft 6, present target azimuth data by shaft 1. present target slant range data by shaft 8, azi muth rate data by shaft 9, and elevation rate data by shft llv Shafts 6 and I also serve to control the orientation of the line of sight 69 of sighting device Ill.

The sighting device It includes a reflecting prism 5m rotatably adjustable about a horizontal axis (in elevation) by a worm gear 552. This worm gear 532 and prism 50! are carried by a main body 5633 that is mounted for rotation in azimuth about a vertical axis. The line of sight is reflected prism till into a reflector but which reflects it to an eye piece 58% whereby a target in the line of sight may be observed and tracked by the operator.

Azimuth shaft l drives a pinion 5536 that rotates the main body about a vertical axis and thus adjusts the line of sight 6.! in azimuth. The shaft 1, representing the azimuth position of the line of sight S9, is also used to drive the present azimuth (A) of a target into the computer. Rotation of the worm gear $82 to adjust the elevation oi the line of sight is eiiected by worm 551 that is driven by a gear H8 meshing with a ring gear 599 which surrounds the main body and is free to rotate relative thereto. The ring gear is driven by pinion. 5 on a shaft 5i? that is in turn driven by the output of a compensating differential Elfl. The shafts 6 and l act through pinions 5M and 515, respectively, to drive gears 516 and 5 l 7 representing the input to the differential Sit. The purpose of the differential is to prevent changes in azimuth from afiecting changes in elevation of the line of sight 69 by rotating ring gear 569 with the main body for changes in azimuth.

From the description, it will be apparent that the shafts E and '5 control the elevation and azi routh positions of the line of sight 69 from sighting device iii. For a more complete description of the sight and computer mechanism, reference may be had to the above-mentioned copending application, Serial No. 411,186, filed September 17, 19 m.

The computing mechanism I actuates a suitgun elevation synchronous position transmitter l2 and a gun az muth synchronous position transmitter 53, whose outputs l4 and Iii comprise voltages corresponding to the proper gun aiming angles, may be used to indicate these angles to remote gunners, or to directly control the orientation of remotely actuated guns in any suitable manner, such as shown in abovementioned copending application Serial No. 424,612.

The present embodiment of the invention is directed towards the provision of suitable stabiliaa-ticn for the computing mechanism I. As is well known, wh n any sighting device is mounted on char .1 'voidable pitching, yawing, and rolling of the c it create great difiiculties when otter ack the sighting device with a swiftly rno ing oricntatio Accordingly, in the present inven n the eficct of such erratic motions of the aircraft carrying the computer-sight is minimized by using a standard or reference of position for the control of the computing mechanism input which independent of the oi" the craft. In effect, the tracking data input to the computing mechanism are resolved into two components, one component representing the motion of the craft with respect to the position which may be termed the stabilization component, and the second com ponent representing the motion of the target with resp ct to the standard of position, which may be teamed the control component, for reasons which will appear hereinafter. Thus, the total data input represents the motion of the target with respect to the craft, so that the computing mechanism may calculate from these data thecorrect gun. aiming angles, with respect to the craft, for efiectively engaging the target.

The stabilization component may be automatically produced by the action of suitable gyroscopes serving as position standards in elevation and azimuth respectively, while the control component may be produced by a manual control serving simultaneously to track the line of sight 69 with the target and to set the target orienta tion data into computing mechanism I.

Thus, referring to Fig. 1, there is provided a suitable tracking control Ii actuated from a handle-bar type manual control it, these being shown more in detail in Fig. 2, where it will be seen that handle-bar control is is adapted to be manually rotated about two mutually perpendicular axes l9 and 2|, axis is being normally horizontal and corresponding to the axis about which motion of the computer line of sight in cles vation is produced, and axis 21 being normally vertical and corresponding to the axis about which motion of the line of sight in az'znuth occurs. Rotation of control l8 about elevation axis !9 rotates a pinion 22 meshing with a circular rack 23, which is thereby translated along axis 2! in accordance with the displacement of control I8 about axis is. Connected to rack 23, as by a suitable rod 24, is a second circular rack 26 engaging with a similar pinion 2'! which is thereby angularly displaced proportionally to the angular displacement of control l8. Fixed to pinion 2? and actuated thereby is a movable arm 28 of a potentiometer 29 energized from a suitable current source, such as a battery 3!. Output circuit 32 is connected between a variable arm 28 and the center-tap 33 of potentiometer 29.

t will, therefore, be'apparent that rotation of control [8 by a predetermined amount in either direction from a neutral position corresponding to coincidence of arm 23 with tap 33 will produce a voltage output in circuit 32 corresponding in polarity and magnitude to the sense and magnitude of angular displacement of control is about axis I9, which will be termed the elevation control signal voltage.

It will be clear that the control just described need not be restricted to the use of direct current, but may also use an alternating-current source in place of battery 3!, in which case the elevation control signal voltage output across wires will be a reversible-phase variable-magnitude alternating voltage. If desired, an auto-transformer may replace potentiometer 29 in such case. Also,

' any other device for producing a signal correspending or proportional to displacement of control member l8 may be used.

Displacement of handle-bar control iii about azimuth axis 2! causes a corresponding angular displacement of a bevel gear fixed thereto. Gear 34 engages a further gear 35 to shaft 35 which actuates the variable arm El of a similar potentiometer 38 energized in a similar fashion from battery 39 or from an alternating-current source. The azimuth control signal voltage, again taken between variable arm 31 and center tap di and appearing in output cable 32, will be of the same type as the elevation signal voltage in cable 32.

It will be clear that rotation of control It about axis is is completely independent of its rotation about axis 2| and the operator is thereby per mitted to make independent or simultaneous adjustments corresponding, as will be seen, to the .6 desired elevation and azimuth adjustments of computer i for effecting tracking with the target.

The present invention is not restricted for use with the particular type of control shown in Fig. 2, although it is to be noted that this control contains the great advantage of providing a natural type of control having a convenient and natural way of operation without requiring decided mental effort on the part of the operator. If desired, any other type of control adapted to produce two independent reversible phase or reversible polarity and variable magnitude signal voltages may be used in place of the control shown in Fig.

Referring once more to Fig. 1, the azimuth control signal voltage appearing in cable 52 is connected through a Suitable switch 33, when in the down position, to an amplifier id of any suitable conventional type adapted to produce in its output, under the control of the azimuth control signal voltage, a suitable control voltage for controlling the azimuth servo it. Servo it may be of any desired type preferably adapted to produce an angular velocity of its output shaft 4? corresponding in sense and magnitude to the sense and magnitude of the azimuth control signal voltage, and hence to the sense and magnitude of. the angular displacement of handle-bar control it about azimuth axis 2 I.

One suitable type of such servo is shown in Fig. 3, although the present invention is not necessarily restricted to this type. Here the control voltage appearing on cable connected to amplifier is through switch Amplifier A l in this instance is adapted to produce in its output a reversible polarity direct voltage which controls a suitable torque motor 5-8 of any conventional type adapted to produce an angular displacement of its output member 59 in a direction and of a. magnitude corresponding to the angular displace ment of control l8.

As shown, output member 5.9 may be central ized by suitable springs 51, which also assure a linear and proportionate type of control. Outputmember is is adapted to reciprocate the control piston of. a suitable control valve which is supplied with hydraulic or pneumatic pressure from a suitable pump as by a duct and is connected to a fluid return reservoir or sump by a duct 5%. Valve is adapted to produce between its output ducts ill and a differential pressure corresponding in sense magnitude to the relative displacement between its piston 52 and movable c der 55.

This ential pressure led to a servo motor hav. g a fixed. piston movable cylinder to cylinder of valve The pressure causes cylinder 5 to move, thereby decreas ing the differential pressure by repositioning cylinder 55 towar ts neutral position with respect to piston In this manner cyl nder 55 is displaced by amount corresponding to the d splacement of arm ie of torque motor 68. It will be clear that valve and motor 5?! provide a booster or servo system for reproducing the displacement of the output 539 of torque motor 43 with increased power. Anv other type of booster or serve system may be used here.

The displacement cylinder 55 actuates the input of a suitable variable device, such as the well-known lickers variable-displacement hydraulic type. which has an input A-end 65 comprising a continuously driven variable displacement pump driven from a suitable power motor 62, the pump displacement being varied by adjustment of a control rod 63 connected to cylinder 55. The adjustable fluid output of A- end 8! is led to the output B-end es of the hydraulic unit, which comprises a fluid motor driving its output shaft 47 at an angular velocity which is thereb proportional to the setting of control member 53. In this Way there is produced an angular velocity of output shaft ll corresponding to the angular displacement of control it, and hence to the desired control in azimuth of computing mechanism l. Any other type of variable-speed drive could also be used.

It is to be noted that control member 63 of A-end iii of the servo as (Fig. 3) may be actuated directly and mechanically from shaft 35 of tracking control ll (Fig. 2) where it is not necessary or desirable during manual tracking to use a re mote control unit I! as in Fig. 1.

Since the displacement of control member 83 represents the rate at which output shaft 4'! is rotating, the rate data required by the computer I may be obtained directly. Thus, also actuated by cylinder 65 is a suitable rack and pinion arrangement 66 actuating a shaft 63. Shaft 67 will accordingly be displaced by an amount corresponding to the rate at which shaft 3-? is rotating. The angular displacement of shaft a? representing the control azimuth (Ac) added to the azimuth stabilization components (Se) to be described, in a suitable differential t3, and the sum of the rotation of shaft ll and the azimuth stabilization component, resulting from the out put of differential 62, serves to rotate shaft 1 and thereby sets the target present azimuth data (As) into the computing mechanism 5.

In operation the gunner will actuate control it which, as has been described above, controls the rate at which the data are set into computing mechanism 1, in such a manner as to cause the optical line of sight 559 of sighting device It, whose orientation corresponds tothe A0 and E0 settings of computing mechanism to follow and track with the target. When this done the required present target azimuth data A0 will be set into computing mechanism i by way of shaft 1.

The standard of position from which azimuth stabilization is derived, is shown as a suitable directional gyro, indicated schematically as l3, having a rotor spinning within a rotor bearing frame H about a normally horizontal spin axis l2. Frame ii is pivoted as by pivots l3 about a normally horizontal gimbal axis within a verti cal ring is rotatably mounted about cortical axis it in pivots carried by the craft.

As is well known, a directional gyro of this type tends to maintain the orientation of its spin axis 72 fixed and in a horizontal plane. Should the craft change its attitude in azimuth, as either by change of course or by yawing, it will be clear that, since gyro ill maintains its orientation fixed, a relative displacement will occur between the gyro spin axis and the c:ait

This change may be sensed by a pick -on", indicated schematically at ll, which may be of any well known type adapt-ed produce a signal corresponding in sense and magnituce to the sense and magnitude of the displacement between the heading of the craft and the directional gyro spin axis.

The output of pick-off T! is fed to a suitable amplifier l8 whose output controls a suitable motor l9. Amplifier l8 and motor 79 may be of any well known type, either direct current or alternating current, adapted to produce a rotation ae was:

9 of motor T9 inone directionor the other se long as any signal is produced in picleoff 1?. Wellknown anti-hunt devices may be used to assure immediatestopping of motor 79 upon cessation of signal from pick-01f 1'5".

Motor 19: actuates a suitable wormand worm wheel arrangement 8!- which, through a crank 82, actsto re osition pick-oh $7 toits neutral position"- with' respect to vertical ring M of gyro m.

The system just described, therefore; opera-fies as a simple follow-up device, causing crank 8 2 and Worm Wheel 81 tofollow-up the positionof the gyro spin axis ii. n 1 so doing,- shaft 833mm nected to follow-up worm wheel 8 is angu any displaced anamount corresponding angular deviation between the gyre spinaxis and the craft ax-i's- By making the foii'ow-up action quite-rapid s'o-that instantaneous ehanges of craft attitude are immediately senseol and correspondingly actuate shaft 83, it will be clear that the angular displacementof shaft 33 W'iiI represent the instantaneous die-viati'on of the craft from a hiredstandarci of position provided by the gyro iii.

Accordingly, thisangular displacement of shaft 83 willrepresent the desired stabilization azimuth (S2) which, as described above,- isadded. to the azimuth control :iata- (A09 in clii fier ential 68 and thereby'serves to stabili zethepres J- ent target azimuth data" (A) set into cornputihg mechanism: i by means of shaft 1, since the op era'tor actuating manual cont 'i- F6- to track with sight; is need com ensate en-i y for themotion of the target with respect to the standard of position provided eireetionaii gyro w, the stabilizing mechanism automatically providing the stabilizeti'on' coinpoi rent. This stabilization of the computer and sight insures a smoother type of tracking and facilitates accurate traeli ing with the target; since the randomflnctuations of the line of produced by themotion off the craft nescii not be corrected by the ochtrol it; but are auton ati'c'al'ly cor-i'eetezi by the stabilizing. gyro it nd i s-assoc'iated equ' hient;

The control of c puti g-mechanism I in elej vat'ion is deriv'ee' in a similar manner, the eTe= vati'on control signal" voltage appearing out put cable's? and heing' e'onnectka'1i through a suitable switch 8'4 toan amplifier 8B; andthereby to the elevation servo 87 Whose output 83 rep resents the elevation control data. 6E5). 'lhese are combined with the-elevation stabilizing data. (Se! in differential 3% toprovide the: present target elevation data; (E's)- as the a-r'i'g'fil'ai displacement-oi shaft" 61- 7 In order to provide the elevation stabilization data, there provided :rsuitable" gym-vertical 951 comprising a rotor spinningabout-a normavlly vertical: axis 35- within a rotor bearing. frame 92 which: is pivotally mounted about a: normally horizontal axis within a horizontal ring 9T, which in: turn is: pivotall-y' mounted about a horizontal axis 9%- Within a bracket 91', rotatable about. a vertical axis preferably coincident with verticaiispin'axis 91 of the gyro 93-;

Bracket 9? is rotated directly from present target azimuth data (A0) shaft 1- asby suitable gearing. 98, shaft 98, and gearingiii-I, so as to maintain axis 83 within the vertical plane ont'aining the target orientation line. By 50' dbihg; it will be clear that any change inthe attitude of the craft with respect to axis QS- willrepresent a change inthe elevation E0 of the target-orientation with respe'ct to the craft.

By a foliow -i'1p-system'simnarto that used with directional gyro it, a motor I02 is causedto-prcduce" a rotation of itsout'putshaft" r63 corresponcling to any" deviation in the attitude of the craftabout axis is With respect to the-vertical standard of position provided by vertical gyro 96L From the discussion above it will be clear that this angular displacement of shaft wi lrbe the desired elevation stabilization correction (so This angular displacementis transmitted asby way of suitable rack andpinion arrangements H34 and I passing through the stern of bracket at to a shaft It? and thereby todifferential 89, wherein: it combinedwith the elevation control data can to form the present target elevation data reor which is" set into" com uting mechanism l by'way 'ofs'hafti 6i.

accordin ly; it wii-r be clear" that n tracking with a: swiftly moving target all erraiicvarianons of' the craftin azimuth and elevation with re-' spect to the vertical and the horizontal aresensed by" directional gyro NJ- and vertical gyro is; and suitable correcfiions are introduced into the com putihg'fiieohaiii'smcontrol, whereby the operator needonly set the control data (EC; Ac)- corresponding to the movement of the target respect to" the vertical" and'hori'zontal standa'rcis of" position. Thereby the line of sight, insofar astne-o eraier is" concerr-ie'cl eiiectivelysta iiliZEd and the changes attitude (if the craft haveneefiiect upon his control; so that the-op ei' ator may more easiiy track the l'ine of sight with a fast-moving target:

Itfs to be noted that thepr'eseiit elevation data (Ea) and azimuth data 6A0) represent the ifi stantaneeuselevation and a-"zinui iih of the target with respect to the cra ft and accordingly the ihii-hg angles (-E' ana (fig) determined by the dfilifiiltifig FER-3G112151119111 are else tiililif6- Sfi'fi tothe crate;- wfierbfftfiey may be directly uti-lizd to bfifirdl e" or the guns, Whih is 131 5817 easilyd'tifie" Vfififi reference fiO fl' l' $1 2,1 1; en which the are mcur mezr liberates Oi hatnge' df azimuth amt elevatien may be obtained. fifl'o'mserve mechanism described with respect to Fig; 3, and these: rates; scenes the: azimuthrate Asl corresponding to the: angmar displa'cem'entof shaft 6 1-, and the elevation rate: (Er) corresponding to the angular displacementofi shaft? I68 are: led by suitable gearing-' and. shafts; to the: respective rate data input-Si 9 and: lit" of! computing mechanism I The present target slant; range data (Do) ro q'llii ed cementing: mechanism I may be pro video by ai-seit'abierange-control pedal- Hie coop: erati'ng a pet "t-io'meter arrangement l lil' whichtherebyprovi'ies a rangesignal volta'g'eofal type similar to the eievatiorrand. azimuth Signal voltages already described. This range signal voltage is fed through a suitable switch u 2;.when in the left osition; trie'range seivo H'iwhich may be of the same type as that shown in an. 3" and; accordingly ac'tuates the range input 8 7 ofcomputingtmechanismp I t. desired; range servo l. i quired by computing mechanism are supplied thereto.

The system just described ma be termed a rate control system, since a given displacement of control it produces a corresponding rate of change of the line of sight in azimuth and/or elevation. However, the present invention need not be restricted to such a type of control, but may equally well be used with pure displacement control systems or combined rate and displacement control systems, known as aided tracking systems.

Fig. 6 shows an alternative system for obtaining the elevation and. azimuth rate data required by the computing mechanism I. The apparatus for obtaining the stabilization correction data (Se) and (SE) has been omitted from Fig. 6, but it is to be understood that the stabilizing apparatus described with respect to Fig. l or with respect to subsequent figures may be used with the system of Fig. 6.

Thus, in Fig. 6 the present target elevation data input shaft 6, which is controlled by elevation servo 37 from control 18 as in Fig. 1,.serves to rotate a platform 40! geared thereto. Platform 40! supports a rate gyro 362, comprising a rotor spinning about an axis 463 within a rotor housing 454. which is pivoted about an axis 486 within a bracket it? supported on platform dill. Motion of the gyro housing M4 about axis 456 is restrained by means of springs 508 connected to arm H and mounted on a bracket 489 also fixed to platform E. Preferably the intersection of axes i113 and 486 coincides with the axis of rotation i! l of platform dill. j

In this manner, as is well known, rotation of platform i applies a torque to rotor housing 384 about the axis of platform 48!, thereby causing precession of the rotor axis 483 about axis 486. In accordance with the well-known theory of rate gyroscopes, the deflection of spin axis $63 is thereby rendered proportional to the rate of turn of platform 69!, and accordingly, is a measure of the rate of turn of shaft 6, so that it represents elevation rate data (Er), This derate data (Er) are set into computing mechainsm i. To permit rotation of the gyro 492 without affecting the displacement of rack M2, the arm 605 extending along spin axis 403 is pivoted to one end of link 542 that has its other end pivotally connected to lever 843 having its fulcrum M l carried by an arm 4&5 extending from the bracket 467. The lever is coupled by a sliding joint M6 to translate the rack in response to movement of the gyro spin axis and arm 495. If desired, or necessary, a power booster of any Well-known type may be inserted to drive shaft II from gyro 5G2.

A similar arrangement, including'a platform H4 and a rate gyroscope M6 mounted thereon, is actuated from present target azimuth data input shaft 2, and serves to displace azimuth rate input shaft 9 in accordance with the azimuth rate data (Ar) in a similar manner. Gearing d5! driving azimuth rate shaft 9 may also be controlled by a circular rack 452 that is translated by movement of arm 853 through link 454 and lever 655 in a similar manner to that described in connection with gyro E92.

Although the system of Fig. 6 has been described as being a rate control system. as in Fig. 1, it will be clear that a, displacement control system or aided tracking system may be used here also, without affecting the operation of the rate data inputs. This follows from the fact that the rate gyros 415 and 462 effectively sense or measure the rate of rotation of shafts l and 6, which, during tracking, have angular displacements corresponding to present target position data, whereby there is produced accurate present target rate data, as required, without regard to the type of control which produces the tracking condition.

Fig. 7 shows a modification of the rate gyro devices of Fig. 6. Thus, here the gyro 492 is mounted on the platform MI by means of a bracket 50? within which the gyro rotor housing tilt is pivoted about an axis 405, as in Fig. 6. Platform 40! is driven from the data input shaft, such as 6. An arm 495 coaxial with the spin axis of the gyro 402 is fixed to the gyro rotor housing 804. Upon turning of the platform W! the arm 495 will rotate about axis 406 in a clockwise or counterclockwise manner depend ing upon the direction of rotation of platform .5L Assuming for illustrative purposes that arm 3% moves in a counterclockwise direction or upward, it then serves to move upwardly the piston :li'f of a pneumatic or hydraulic pilot valve tit of any conventional type, adapted to produce in its output ducts M9 a differential fluid pressure corresponding in sense and magnitude to the displacement of piston 4I1. This differential pressure is lead by ducts i 19 to a servomotor 42 i and is applied to the opposite faces of the piston 422 thereof.

Fixed to piston 422 are the gyro centralizing springs 5238 which tend to maintain arm 4&5 in a centralized position. Thus, the differential pressure created by valve -llB is led to servomotor 32i in such sense that one or the other of the springs its will resist the motion of arm 495.

In effect, piston 22 in the illustration used would be forced downward by this differential pressure until the downward force transmitted through the springs 468 to shaft M5 is sufficient to counteract the torque tending to rotate arm 355 upwardly due to the rotation of platform 46! An equilibrium condition will be reached in which shaft 6% has been returned to substantially the same position it assumes when platform iii! is at rest.

Since springs 458 are linear devices, it will'be clear that the displacement of piston 422 necessary to produce this equilibrium condition will be proportional to the torque exerted by arm 4215 and therefore will be proportional to the rate of turn of platform 69 l.

Accordingly, this motion of piston 422 may be used to-set in the required rate data into the computing mechanism 1. As shown in Fig. 7, this may be done by means of a suitable rack and pinion arrangement Q27 actuating the rate input shaft ll. Preferably, rack 521 is made circular in shape and concentric with the axis of rotation ii i of platform mi in order that the rotation of platform 48! shall have no effect upon the transmission of the rate data from piston 422 to rate data input shaft i I.

It will be clear that this device of Fi 7 may be used both for the elevation rate data input and for the azimuth rate data input to computing mechanism i in place of the corresponding portions of Fig. 6.

In the system of Figs. 6 and 7, the spin axis of gyros 402 and M6 may be arbitrarily oriented assessewith respe t t the craftin which; th y are moun e so one a he. ste i used; only with ra ght ine i he craf hould the c a t be turning, however, it is, possiblethat false rates will be produced, due; to the response of gyros 2; an as to th angu ar v locity o the af Accordingly, it is desirable to maintain the spin axis of azimuth; rate gyro 41 6 oriented in a. vertical direction with respect to, the craft. whereby the. angular; velocity of turning; of the craft, will b n tive to p oduce f e; utput. from y o ii 5. Should angular; velocity ot the craft in pitch: about the line of sight or target orientation be; material, the spin axisoi elevation rate gyro maybe maintained horizontal and perpendicular to the line of sight, by apparatus similar-tolera e; t a i s as ocia ed equi ment of Fig; 1, whereby any angular velocity'of; the cra f't about the elevation; axis of; the. lmeoi sightlis also ineffective.

The er ion s b liz ng-sys em. de bedwi .552 0 Ei most; att n ve 0 1 5! Wher he attitude of the craft; deviates; little; with respect. he o n. a dard provid d-bye ic -I gyr Sil sinceit will beseen. that for large-displace:- ments the rotation of bracket 9'! may introduce precessing; torques due to. girnbal friction which w d d tu he re er nc pos t on of gyro.- 9B.

To overcome thi s clef ect the stabilization device shown Fig. emaybe Substitutedfor thatiof F m s n is ns nce: r cal. yro; 995 s p a e ita furtherdirectional gyro- H5 having a. rotor" spinning about a horizontal axis H8 ithin, a. rotor bearingframe HI pivotally mounted about a vertical axis IIB within the vertical rine; He;

lar to Fig. 1, to keep axis; sit-perpendicular; torthe line of sight. It will be; clear; tha-tany; rotation. of: bracket 51; about the vertical; axis willtend.

to produce a. rotation. of vertical; ring; Hit-with respect to rotor frame. v H1, since; the spin, axis; l I 6-. of; gyro i tends to;remain.- fixed in space.

However, the. present device the: spin axis;

i It i iscaused to remain perpendicularto. horizontal axis Stat; all times byi'the operationv of a SUltihblBfOlIQWrHD systemcomprising; a pick-on iii, a follow-up amplifier. I22 andza torque-mos.

o A y ev a i n oir pin ie m a:

condition of perpendicularity with respect to pivot: a is 5 s e i npickr fi. 4 h-b duces suitable signal voltages amplified in follow.- up amplifier- I22 and then fed; tov a conventional torque-creatingdevice i2 3, which createsatorqueabout axis 96. thereby processing. thegyro-rotor- Ill about-vertical axis H8 until spin axis Ila-is again correctly oriented,

Inthis ay, spin axislifi is maintainedin a horizontal positioninthe vertical plane contain ing; the line; of. sight 69;.

vation ofthetargetwith respect tothe craft, during tracking.

Afollow-up device; including motor; Hl2, is;p ro

vided similar to that in; Fig; 1:; and provides an:

angular displacement:of its outputshaft Ifl32pr0- portional to the change inattitude; of the CIaQE-ti about-a i t es cttov e. o it a d ard defined by gyro; H Accordingly i this. --rota-.

tion pr sentsthefleshede t stabilizationcorrection (Se) diseussed above and theidevice ofg Consequently any; changes in theattitude of; thecraft-occurring about axis $81 will represent: changeszin the-elerr is Fig. 4% may therefore be substitutedv for the corresponding portion of: Fig. i.

The system of: Fig. l; or Fig; 6 is also adapted for use with a remote sighting device such as a remote telescope, soundlocator, searchli-ght, etc; or a, remote radio sighting device similar to that; described in copending application Serial No. 441,188. Such a sighting device: is. indicated schematicallyin Fig. 5 illustrating: a line-ofsight-defining member 121% shownv as being. an optical telescope. It is to be understood that any other line of-sight defining device may be used. Telescope I24 may be pivoted abouta horizontal axis such as 126 carried by av bracket 12?, itself. rotatable; about a vertical axis 28. Suitable means for controlling; telescope [2:3 either manually or remotely may be provided but. are. not shown in this figure:

Coupled to axis I255 is a, suitable elevation seltsynchronous. transmitter i29- of any welleknowntype: whose output cable [38: thereby contains sig: nal'voltages representing the position of telescope [24: in elevation. A similar azimuthv self-sym chronous transmitter i3! is suitably coupled to.-

bracket i 21 torep-resent the azimuthpcsition of placements between the orientation of sighting device I'M-and the orientation control data se ting (Ac, Ec) of computing mechanism 5..

These control signals are connected through switches 8% and ii-2, now in. the upper position corresponding to remote controhto amplifiers 3% and as controlling'the servos i and 4%) in the manner described above. Accordingly, the azi'-- muth and elevation control of the computing mechanism 1 is new efiected merely by tracking with: the target by means of sighting device 524, which; may be manually or automatically aetuated in any desired. manner.

In the present; case itwill be clear that sighting device E24 does not have its line of sight c stabilized in the same manner astheline of sight Q9 05 Fig: 1. If desired; as shown in Fig. 1, signal generators i-33 and ltd may be actuated directly by thetargetposition-data, by coupling them re.-

spectively to shafts 5 and I. In such a case;.the-

computer data stabilization provided by gyros 1e and 90 will be. inefieotive, since no matter What corrections are derived from the gyros, servos 8'5- and will be. so actuated as to maintain shafts 6 and 'iin correspondence with the respectivecomponents of the orientation of sighting device. l24.

In order to provide proper stabilization for the li-ne-ofsightof the remote sighting device, re-

course may be had to the system of Fig. 8. Herev Thu s,:. .in azimuth, computer: i will be provided with an-azimuth control self-synchronous transs mitter such as i 39 which maybesuitably coupled to shaft t! (Fig. 1). If desired, signal generator 335 of Fi 1 may serve as transmitter Q39 by suitable well-known circuit connections.

Transmitter its is connected to the (Ac) signal generator ME in whose output I 22 there is generated a signal voltage in accordance with lack. of correspondence between transmitter E39 and signal generator f ll, representing relative displacement between the setting of computer I and the orientation of device 124, as will be seen. This voltage is fed to any conventional type of followup device its whose output repositions signal generator :4 in correspondence with transmitter lee. In this way, output shaft Via-'3 of the azimuth follow-up Mi l is positioned in correspondence with shaft 4! of computer i as shown in Fig. l.

Similarly, the output of the azimuth stabilizing apparatus comprising the angulardisplacement of shaft actuates a suitable azimuth stabilization transrn' ter M! which in similar fashion is connected to an azimuth stabilization ial generator controlling the (Se) followup 559 which positions its output shaft i-5i in correspondence with the position of shaft 83 of Fig. 1.

The angular displacements of shafts i 25 and lfii are combined in differential H32 whose output 553, during tracking represents the present target azimuth (A) Shaft IE3 then controls the orientation of the line of sight of sighting device its in azimuth in a manner similar to that which shaft i controls the device it as described in connection with Fig. 1.

In a similar manner, elevation control data (EC) appearing on shaft 38 is used to actuate a suitable transmitter i 'i, signal generator and follow-up i'i, to position shaft 158 in correspondence with the (Eb) data, and the elevation stabilization data (Se) appearing on shaft i ii? actuates a suitable transmitter itt, signal generator E63, and folow-up 352 to position shaft it? in accordance with (Se) data. The angular displacements of shafts I53 and I63 are combined in differential 554 to actuate the (E0) input thereby controlling sighting device i2. a manner similar to that in which shaft 5 controls the elevation of the sight it in Fig. 1. It is to be understood that follow-ups :32, Eel, 49 and. M l may include any necessary or desirable amplifiers cnti-hunting devices.

In this manner, sighting device are, even though remotely situated from computer i, may replace the built-in optical system it that defines the line of eight 59 in Fig. 1. Manual control it, 5-3 (Fig. 1) also be remotely situated. As described above, si hting device lid need not be a purely optical device such as a telescope, but may comprise a radio-locator, an infra-red tracking device, a searchlight, a sound locator, supersonic locator, or any other device defining an effective line of sight adapted to be tracked with a swiftly moving target.

The system just described corresponds closely to that in Fig. l, and operates in a similar manner. The ope ator actuates manual control it? until the line of ht of sighting device @245 coincides with the t rget orientation, at which time the proper data are set into computer 1'. Since sighting device is stabilized similar to that of Fig. l, the operator need correct for the motion of the target only with respect to gyros lil and Si and hence with respect to the earth, so that a completely stabilized system is obtained. If desired, the stabilizing apparatus may be located directly at the sighting device i34 If it is desired to control sighting device 12 from any other apparatus, such a suitable radio circuit similar to that described in copending application Serial No. 441,188, control of the azimuth and elevation follow-ups and i5? may be derived from any source of signal voltage connected to their inputs. However, in this case the sigh ing device I24 will still remain stabilized since the stabilization data (Sa) and (Se) from computer i are still effective in assisting to orient sighing device I26 by means of its data input shits and 55. Sighting device 22:": may then control computer i in the manner described with respect to Figs. 1 and 5, thus providing an entirely automatic and stabilized fire control and tracking system.

Fig. 9 shows a further and preferred modification of an optical sighting system with apparatus for stabilizing the input to computing mechanism i, in this instance using a single gyro I!!! both for stabilization and for the production of the rate data required by computing mechanism i. It is to be understood, however, that the rate data deriving apparatus of Figs. 6 or 7 may be used in place of the corresponding apparatus of Fig. 9.

Gyro llil comprises a rotor ill spinning about an axis il2 gimbaled within a ring H3, which is pivoted about an axis iM perpendicular to spin axis ['52 and gimbaled within a further rin H5. Ring ill) is mounted pivotally for rotation about an axis I'll perpendicular to axis Il within a follow-up ring H8, which is also pivoted for rotation about axis ill within a bracket l'i Bracket iii in turn, is pivoted about a vertical axis Hill. 7

Gyro lit in this instance is a free gyro, adapted to have various control precessing torques applied to it. Thus, a torque may be applied about axis lit by rotation of a pulley 532 connected by means of springs let to extending arms i$3 fixed to or integral with pivot axis PM. Rotation of pulley H32 in one sense or the other will produce a corresponding tension or compression in springs I34 and will thereby produce a torque on ring E13 and gyro rotor ill about axis i'l i. Furthermore, by the use of springs Hi l, the torque applied to ring H3 will be linearly proportional to the angular displacement of pulley E82.

In a similar manner, by means of a pulley H36 and springs 18? fixed to projections its on ring H6 a corresponding torque may be applied to ring I16 about axis ill. Here again the torque applied is proportional to the angular displacement of pulley lat.

Follow-up ring H8 is caused to remain in a plane perpendicular to the spin axis 112 of gyro iii). For this purpose a pick-off, conventionally represented at 189, is provided for sensing relative displacement between spin axis Hi2 and follow-up member E78 about axis i'i'f. The output of pick-off its is suitably amplified in a followup amplifier iiii, which, through leads :92, controls a follow-up motor F33. The output shaft 9 1 of motor i553 acts through a difierential ISE, whose function will be described hereinafter, to rotate a member 519 ficatingly supported about axis 18!. Member H9 causes rotation of gear 593, shaft I99, gearing Elli, shaft 282, and gearing 203, to rotate gear sector 2%, which rotates follow-up ring i'ld about axis ill to return pickoff 189 to its neutral position. In this manner, by proper design of the follow-up ltd, lei, I93, follow-up ring H3 remains in correspondence with the spin axis 172 about axis ill.

A second pick-off 20B senses relative displacement between follow-up ring I18 and spin axis I12 about axis I'M. Through the operation of pick-offs Hit and 205 and their associated circuits, spin axis I12 is always maintained perpendicular to the plane of follow-up ring I18, The output of pick-off 2% is fed to a follow-up amplifier ZIl'I controlling a follow-up motor 288, whose output shaft 2% rotates bracket I19 about vertical axis ISI and thereby serves to reposition follow-up ring I 78 into correspondence with spin axis I12. In this manner, spin axis I12 is always maintained. perpendicular to the plane of follow-up ring I18.

Spin axis I72 is maintained oriented toward and tracks with the desired target, as will be described hereinafter. Accordingly, the angular displacement of follow-up ring I78 about axis I77 from a predetermined neutral position will represent the actual elevation (E) of the target. Since this angular displacement is proportional to the angular displacement of output shaft I94 of follow-up motor 593, it will be seen that this shaft I94 may be coupled directly to the present target elevation data input shaft 6 of computing mechanism I to supply the required present target elevation data thereto.

In a similar manner, the angular displacement of spin axis I12, and hence of follow-up ring I78 which maintains fixed relation thereto, about axis ISI, will represent the actual present target azimuth data (A0) required by the computing mechanism I and, accordingly, output shaft 209 of follow-up motor 293 may be coupled directly to present target azimuth data input shaft I of computing mechanism I to supply present target azimuth data thereto.

The apparatus for causing gyro spin axis I'I2 to track with the target will now be described. It is to be understood that a suitable orientable sighting device I l capable of indicating coincidence with the target orientation is provided, and is coupled as in Fig. l to shafts 6 and I to maintain the line of sight E9 coincident with that of spin axis I12. For operating the system, a manual tracking control device I'I, similar to that described with respect to Fig. 1, is actuated by a tracking control I8 to provide in its cutouts 42 and 32 the respective azimuth and elevation control signals necessary to maintain the si hting device oriented toward the target. The elevation control signal is conducted by cable 32 through switch 84 (in the down position) to am lifier 86 and thereby causes a pro ortional dis lacement of the output member 49 of toroue motor 48', which actuates the control valve 53' to create a displacement output from servomotor 60' in the manner described with respect to Fig. 3. Any other type of servomotor could be used, or it could be omitted entirely if the output of torque motor 48 is sufiiciently powerful.

This displacement acts through a suitable rack and pinion arrangement 2H to rotate pulley I82 correspondingly. It will be clear that the rotation of pulley I82 thereby produced will be proportional to the control signal, and, accordingly, a torque will be applied by springs I84 to gyro ring H3 about axis H6 proportional to the elevation control signal. As is well-known, when a torque is applied about one axis of a gyro which is likewise unrestrained, its other axis is caused to precess at a velocity proportional to the applied torque. Accordingly, he torque applied about axis ii i causes a precession about axis IT! at, a, rate proportional to the an-plied torque and between the slant plane just mentioned and the coupled thereto.

.mechanism I. shaft 2E2 coupled to pulley i82 by suitable gearis hence proportional to the elevation control-signal derived from cable 32.

.Hence, again we have a rate type of control whereby a fixed displacement of tracking control I8 will produce a proportional angular rate of change of the line of sig t, represented in this instance by spin axis Il-Z or the sighting device When the desired tracking condition obtains, it will be clear tha the proper present target elevation data (Eb) are set into computing mechanism I, since, as already described, follow-up ring I78 is caused to accurately follow the orientation of spin axis H2 and thereby sets in the proper elevation data into the computing mechanism I. Also, since the angular rate of change of spin axis H2 is proportional to the torque applied about axis I'M, and is there- ,fore p-roportional to the angular displacement of pulley I82, it will be clear that this latter angular-displacement may be used directly to set in the elevation rate data (Er) into computing This is done by a suitable flexible ing 213 and connected to the elevation rate data input shaft Ii of computing mechanism I.

The azimuth control signal derived from manual control I? is led by cable 32 through switch '43 (in the down position) to amplifier 54 which controls the torque motor is whose output member 4e actuates the control valve 55 and thereby creates a proportional displacement output from servomotor fill, in a manner similar to the elevation control system already described.

As was seen above, the azimuth control torque applied to gyro Hi! is applied about axis Ill and creates precession about axis I'M. Axis IM, however, does not remain vertical but remains conof a given angular amount may be approximated by multiplying a change in true azimuth equal to the slant plane azimuth by the cosine of the angle of elevation which, of course, is the angle horizontal plane.

It is desirable to have the control signal output of manual control device I? represent the true azimuth rate. Accordingly, it is necessary to convert this true azimuth rate into slant plane azimuth rate before applying the corresponding torque about axis Ill. This conversion is produced by a suitable three-dimensional cam 214 which is adapted to be rotated in accordance with the angle of elevation from shaft I94 of elevation follow-up motor I93 by means of elongated pinion 2IS and to be axially translated in accordance with the desired true azimuth rate by 19 H1 and produces the required rate of change of spin axis E'i! about axis Hi3 as already described.

As already described, the displacement of housing 63 is proportional to the true azimuth rate. Accordingly, this motion may be used to set in azimuth rate data (Ar) into computing mechanism This is done by coupling the azimuth rate data input shaft 5 to shaft 2L9 by means of gearing 227. In this manner, by the usual rotation of handle bar it, the operator may cause spin axis iii. to accurately track with the target and thereby sets into computing mechanism 1 the required orientation data and rate of change of orientation data. The range data (Do) may be supplied to computing mechanism l in the manner already described with respect to Fig. 1.

Instead of utilizing the displacement of tracking control it as true azimuth rate, it may be used as slant plane azimuth rate. In such a case, the output of servomotor 69 would be connected directly to flexible shaft 225 to control precessing of gyro i'il, while the azimuth rate input shaft 9 of computing mechanism i would be actuated from the output or a three-dimensional cam similar to 2 i 4 but adapted to yield an output corresponding to true azimuth rate when actuated by elevation and slant plane azimuth rate data. Such a cam is called a secant cam since it serves to mutliply slant plane azimuth rate by the secant of the elevation angle to produce true azimuth rate.

If desired, computing mechanism I may be modified to carry out its computations of gun aiming angles using slant plane data, which is later converted by a similar cam arrangement to the proper gun aiming angles referred to the horizontal, using true azimuth.

It should be clear from the above description that the line of sight defined by the spin axis of gyro H0 or the sighting device controlled thereby is stabilized. Thus, considering for the moment the condition where the target is fixed with respect to the earth and the sighting device is oriented toward it, it will be clear that spin axis I72 will remain oriented toward the target despite any changes in attitude of the craft (assuming its position also fixed with respect to the earth). Accordingly, the orientation of the sighting device with respect to the earth also remains fixed and toward the target. However, as the craft changes attitude, follow-up motors 93, 203 will operate to change the orientation of the sighting device with respect to the craft, thereby setting into computing mechanism I the proper orientation data with respect to the craft, as is necessary to maintain the sighting device and the gun turrets properly oriented toward the target as the craft changes attitude. Hence, no control action by the operator is necessary in this case. Where the target is moving with respect to the earth, the operator actuates his controls only to correct for changes in the target orientation with respect to the standard of position given by the gyro H0, without regard to any variations in attitude of the craft, which will have no efiect upon his control or sighting arrangement. However, the data supplied to the computing mechanism will all be with respect to the craft, since bracket I19 and axis H! are mounted on the craft, whereby angles of elevation and azimuth are measured with respect to the craft. Hence, the gun aiming angles (Eg) and (Ag) determined by computing mechanism 1 will again be taken with respect to the craft as the datum, and will provide proper indication or control for the guns. There is thus provided, in simpler fashion, a fully stabilized system similar in its results to that shown in Fig. 1.

In a manner similar to Fig. 1, the line of sight defined by spin axis I12 may be actuated from a remote control unit, such as that shown in Fig. 5 or of any other type, by throwing switches 43 and 84 to the up position, in which case amplihers A l and 86 are controlled by relative displacement between the orientation of the sighting device I 2 and the computer setting as described with respect to Fig. 1, the manner of control being as just described with respect to Fig. 9.

However, this system has the same objection as the system of Fig. 1, namely, the actual line of sight of sighting device 524 is not stabilized. To overcome this difiiculty, recourse is had to the system of Figs. 10A and 1013, taken jointly together. In this instance the sighting device I24 of Fig. 5 is illustrated as being a radio scanner 23! of the type disclosed in above-mentioned copending application Serial No. 441,188. As is described in this copending application, scanner 1 23! comprises a directive radiant energy transmitting device 232, whose directivity axis is caused to describe a cone during tracking operations. The axis of this cone is made to follow and track with a distant target, either by manual means or automatic means. For this purpose scanner 23! may be angularly displaced about a normally horizontal elevation axis such as 233 and a normally vertical azimuth axis such as 234-, the motion about elevation axis 233 being under the control of a suitable elevation servo unit 236, and the motion about azimuth axis 234 being controlled by a suitable azimuth servo unit 231, these servos being shown in the present instance as each comprising a variable-displacement hydraulic transmission such as of the well-known Vickers type.

Fixed to scanner 23l and oriented therewith is a gyro 238 similar to gyro I'm of Fig. 9. Gyro 238 comprises a rotor spinning within a rotor housing 239 about an axis 24E. Housing 23!! is pivot- 1 ally mounted within a ring 24?. for rotation about an axis 242 perpendicular to axis 2M. Ring in turn is pivotally mounted within further ring 246 fixed with respect to the scanner 23l for rotation about an axis 244-, perpendicular to axis 242. Pivoted within ring 246 about an axis 2m perpendicular to axis 244 is a bail ring 248, containing an opening 249 through which passes a shaft 242! coaxial with the spin axis 24-! In this way the bail ring 248 is made to rotate about axis 24! together with the spin axis 2 .4. The use of bracket 245 fixed to scanner 23E assures that axis 244 remains perpendicular to the line of sight, and eliminates the necessity for ring i ill of Fig. 9, thereby effecting a great practical advantage and simplification in construction.

In operation, the spin axis 2M is suitably actuated to track with the desired target; that is, the orientation of spin axis 24! is made to coincide with the orientation of the desired target. This may be done by the use of manual tracking control device I! actuated by tracking control i8 similar to that shown in Fig. 2. The elevation control signal thereby produced in the output cable 32 is led through switch 84 and a suitable amplifier 25! to a torque creating device or torquer 252, adapted to apply a torque to bail ring 2% about axis 241. Torquer 252 may be any suitable device adapted to create a torque corresponding in magnitude and sense to the magnitude and polarity or phase of the control signal swears-s voltage" applied thereto; It desired, the torque producing means shown in Fig. 9 may be' us'ed', but preferably one of the well-known electromagneuetorque motors is" used. Such motors may also be used in Fig. 9. The torque thus applied to bail ring 248 is transferred to the spin axis 24! by means of the opening 249', and thereby creates a torqueon the gyro rotor about axis 242'; This torque, as is well-known, will create a; precessing motionof spin axis 24"!" about the perpendicular axis 244', which motion thereby corresponds to a motion of the spin axis 241 in elevation. I

In a similar fashion the azimuth controlsignal voltage produced in output cable l2 of tracking control H is' led through switch 43 to a suitable amplifier 253, and thence to a second torque creatingdevice" 254; adapted to create a torque on ring" 26-3 about axis 264. This torque therefore creates a precessing motion of spinaxis 24! about axis 242. This motion corresponds to motion of s in axis 241- in slant-plane azimuth, as described above. A-ck'zordingly, by suitable manipulation of handle bar control [8- the" fire control officer may maintain the spin axis 24! oriented toward the distant target.

order to" determine when this condition obtains the scanner 23I is caused to track with the gyro 238; that is, the orientation of the axis of the conical scanning ofthe directivity axis of scanner 23! is maintained coincident with the orientation of the gyro spin axis 241'. For this purpose suitable pick-offs such as those shown in Fig. 9, but indicated schematically at'256 and 251, are provided, which sense any relative displacement along two independent coordinates between the spin axis 241' and the scanner orientation. The resulting voltages produced in pickoffs 256 and 21'! are" conducted through respective elevation and azimuth amplifiers 253 and 259' to the respective control circuits 2'6l and 262 controlling the elevation and azimuth servos 236 and 231. Such piok ofis, amplifiers and controls are well known in the art and need not be further described here; In thismannerany relative displacement between spin axis 241 and the orientation of scanner 231 is used to provide a correcting effect to're-orient the scanner orientation into coincidencewith the spin axis 241'.

mthe manner described in the above-mentioned copending application Serial No. 441,188,

periodic pulses of radiant energy are projected from the antenna232, and pulses reflected from a distant object such as the desired target are received by a1 '.tenna 2-32 and are led to a suitable radior'eceiver' 263, as'by means of highfrequency conductor 264. The output 268 or receiver 263 is conducted to a suitable cathode ray indicator 261 on whose screen the relative displacement between the target orientation and the scanner orientation is indicated, as described in copendmg application Serial No; 4411-88. Since the scanner orientation ismaintained coincident with the gyro spin axis 2M", it will be clear thatthis indication also represents the relative displacement betweenthe gyro spin axis 24 and the target orientation. Therefore inoperationthe fire control offic'er will manipulate the tracking control I8 in sucha manner as to maintain the indicated error shown on indicator 267 at zero,

in which case the gyro spin axis 2 and the scanner orientation are maintained coincident with the desired target orientation.

Suitably coupledtothe elevation and azimuth axes 233 and 234 of scanner 23| are the elevation and azimuth self syn'chron'cus' position transmitters-1268 and. 269; which may be'i'ofianywellknown type adapted; to produce in. their"; outputs 211 and 212'? voltages corresponding.- toathe: relative angulari'positionsin elevation. and: azimuth ofthelscanner' 231; Theseposition voltages are led to respective"self-synchronous signal generators213and 214" which areadapted, asxiswell known; toproduceinitheir' outputs 216 and 2-11 voltages corresponding to the" relative displacement between I the respective elevation and: azimuthcomp'onentsof' the scanner orientation and the' angular displacements or their" respective input shafts 278 and 219, which are" coupled respectively to'the'present target elevation data input shaft 6*: and: the present azimuth data input shaft 1. The signal voltages produced" in outputs 216 and 2 71 of; signal generators: 213 and 214 are supplied t'orespective elevation and azimuth follow up circuits 28! and 282 of" any well-knowntype which" operate. to reduce: these signal voltages toze'ro byrotating shaftssS-and into correspondence with the" elevation: and azi: muth components of the scanner orientation. Follow-ups 281, 282'may" include'any necessary or desirable amplifiers and/or anti-hunt and anti-lag devices; Inthis way therequired-present target elevation and azimuthdata are supplied to computing mechanism i.

As described above, the torque produced by torquer's 252, 254" is preferably proportional to the currents applied thereto from amplifiers525tl, 253, thereby producing proportional angular ratios of motion of spin axis 24 in elevation and azimuth. These currents may therefore be usedto set the required rate data intocomputing mechanism 1. Thus, the elevation an'd azimuth control voltages produced incables 32 and 42 by orientation control IT are conducted, as by cables 263, 284', to therespective elevation and azimuth rate follow-up devices 286' and 28! adapted to produce anangular displacement of their output members corresponding in sense and magnitude tothe phase or polarity and magnitude of these respective control voltages. It is tobe understood that-the follow-up devices 266 and 281 may include any necessary or desirable amplifiers and/ or anti-hunt and-anti-lag circuits. Their output members are connected respectively tothe elevation and azimuth rate input members H and 9' of computing mechanism i and serve to introduce the elevation and azimuth rate datainto the computing mechanism. As discussed relative to Fig. 9' the azimuthal motion of spin axis 2' is really in the slant plane.

' Hence the control signal produced in cable 284 and the resulting displacement of output shaft 9 of azimuth rate follow-up 2'81" correspond to slant plane azimuth rate. The true azimuth rate may be obtained by use of a three-dimen sional cam similar to cam 2M of Fig. 9, but used inversely to obtain true azimuth rate data from slant plane azimuth rate data and elevation data. Such a cam is to be understood as included in the computing mechanism I of Fig. 103.

Cables 263, may alternatively be connected directly to torquers- 252 2 54'. This is preferable, since then the possible distortion of the rate signals by amplifiers 251 25 3 is avoided, and the input to' rate data follow-up devices 286, 281 will correspond directly and exactly to the rates of precession of gyro 238.

If desired, computing mechanism 1" may carry out all its computing operations inthe slant zont'al plane, as discussed relative to Fig. 9.

Accordingly, the required rate data and orientation data are provided for the computing: mechanism i. Slant range data may be set into computing mechanism i in the same manner in Fig. 1 or, alternatively, may be set in auto matically in the manner shown in the abovementioned copending application, Serial No. 441,188. Computing mechanism i thereby determines the proper gun aiming angles (E and (Ag) which serve, through the self-synchronous transmitters i2 and E3 already described, to control or indicate the orientation of the guns and/ or turrets.

It will be clear that here also the present target elevation and azimuth data set into computing mechanism 5 will be values determined with respect to the craft, since the voltages transmitted by the elevation and azimuth position transmitters 253 and 259 are also taken with respect to the craft. In addition, the scanner orienta-- tion is stabilized by means of gyro and therefore will not experience the variations due to random change in craft attitude. Accordingly the only control required from the fire control onicer or gunner will be that required by motion. of the target relative to the earth without regard to the change in attitude of the craft. For this purpose the follow up system between the gyro 23S and the scanner 235 should be made quicln acting in order that the scanner 2%! may maintain coincidence with gyro 238 even during fairlyrapid changes in attitude of the craft.

If desired, scanner 22H may be automatically oriented towards the target, in which case switches 43 and 8:3 will be thrown to their left or automatic" position, in which torqu rs 252 and 254 are controlled from receiver 3, by means of respective amplifiers and as shown in the above-mentioned copending application Serial No. 441,188. In this type of opera tion, the scanner orientation is automatically aligned with the target orientation whereby present target elevation and azimuth data are automatically set into computing mechanism 5. In addition, any change in target orientation with respect to scanner orientation serves to produce signals output from amplifiers 288 and which are fed to the torquers 252 and s to realign spin axis 24! toward the target and, hence, to realign scanner 234 with respect to the target. The rate at which the spin axis 24! moves is therefore determined by the rate at which the target is moving with respect to the scanner orientation, and accordingly the voltages required by the torquers 252 and 25 will be proportional to this rate, along the elevation and slant plane azimuth components. Hence, the voltages fed to the rate follow-up devices 285 and 228i are proportional to the actual target rate components and therefore supply computing mechanism l with the required elevation and slant plane azimuth rate data in a manner similar to the manual control already described. Indicator in this instance merely serves as a monitor to show proper operation of the system.

If desired, the apparatus of Figs. 10A and 1013 may be used with a local optical sighting device, whose azimuth control shaft 295 is coupled directly to the target present azimuth data input shaft 7 by way of gearing 29! and 292, and whose elevation control shaft 295 is coupled to the present target elevation data input shaft 6 by way of gearing 293 and 29 5-. These shafts 295 and 296 control the orientation of line of sight 69' in a manner similar to that described for 24 controlling the line of sight 69 in connection with Fig. 1.

When using visual tracking with this local optical sighting device, the operator will manipulate tracking control member la to maintain the target image centralized with respect to a suitable reference index in the sighting device. By so doing, he operates gyro 238 and scanner 23! as well as computing mechanism 4' in exactly the same manner as during manual tracking by means of indicator 25?, but relying instead upon visual sighting to show the desired tracking condition. The sighting device H3, however, will still be stabilized by the action of gyro 238 in the manner already described, since it is coupled to data input shafts (i, l. 7

If desired, scanner 215i and gyro 238 may be located together with computing mechanism I and manual control l8, instead of remotely as shown. In such case, follow-ups 23! and 282 may be replaced by direct mechanical connections between scanner 2%! and data input shafts 6 and l.

It is to be understood that any or all the servos and follow-up devices used herein may be provided with well-known anti-hunt and anti-lag devices.

As many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Having described our invention, what we claim and desire to secure by Letters Patent is:

1. Fire control apparatus for aircraft comprising a sighting device mounted on said aircraft, means for tracking said sighting device with a target comprising means for actuating said device at a rate corresponding to the angular velocity of said target and means for further actuating said device in accordance with the relative changes in attitude of said craft, whereby actuation by said first actuating means necessary to maintain said sighting device in track with said target is unafiected by changes in attitude of said craft, means coupled to said sighting device for setting target position data into a computing mechanism adapted to determine correct gun aiming angles when set in accordance with the target position data and target rate data, and means responsive to said first actuating means for setting in rate data to said computing mechanism.

2. An aircraft gun sight and computer system comprising a target position data shaft and a target rate data shaft adapted to supply target position and rate data to a computer for determining gun aiming angles when said shafts are respectively set in accordance with data representing the position and apparent angular velocity of a target, means including sighting means for seting said position data shaft in accordance with the present position of a target, a gyroscope flexibly restrained about a first axis, means for rotating said gyro about a second axis by said position data shaft, means operated by said gyroscope for producing a differential pressure corresponding to the precession of said gyro about said first axis, the flexible restraint of said gyro about said first axis including linear force exerting means controlled by said pressure for restraining said gyro from precessional disgames laeeme t and; a s er actua in aid rate data shaft in 'acc ordanca. with the displacement, f, sa d. f ce exe t ng m ans A arenas un sight and, computer sys em com ri a, ar t 9 5 ata ha t an ta get ratedata aft, dapted to supply arget DQsition, andf ate data, to a computer for deter: miningmamas angles. h sa d. h s:

ne u n si t ns. me ns ee ettin 5 position data shaft in accordance with the pres i a as. a. e 'uln. aiimns al les, wh n. a e; pans a e. teases..- ma set n eeie iiqeaee vim a a sn s eet a the osit on and e q ty Q a. ar t means ud gh in mea s er ett ?:i; ?L+ as f t a'aeeerd nqe. with i pr ent, ee lij i a a et a. iKQSFQ QfiS X R X r strained; about a fi s mean er r tat n said: 8W abeiiti a n as y. ai es tiea e a a t and ineans"responsive'to the torque exerted; by th'e'said' gyro about said f rstaxis for; setting; saidrate data shaft proportionally to the rate (if-movement of sai'd target position data shaft.

5. 'An aircraft; gunsight andcomputer system comprising a targ'etpdsition data shaft; and a target rate data shaft adaptedtosupply target position and rate data to afcomputer for-determining gun aiming angles when said; shafts are respectively set in accordance with data repr'e senting the. position and velocity of a target; means including sighting means for settingsaid; position data shaft in accordance-withthe present position of a target, a nd a rate gyro responsive to setting of saidposition data shaft for setting said rate data shaft in accordancewith the apparent angular velocity of: said target.

6; A rate of turn responsive device comprisinga rotatable platform, agyroscopehaving a rotor pivotally mounted-about'an axis parallel'to said=- platform within a bracket fixed to said platform whereby rotation of:said= platform is transmitted to saidgyro. rotor, a pilotrvalve controlled by motion of.-said rotorahoutsaidaxisrfor produc ing a difierential pressure corresponding t in .mag-. nitude and sense to the magnitude and-sense, of displacement. of: said: rotor about said axis, a control cylinder. having a displaceable piston responsive. to. said: pressure, and spring means actuated by said piston for applying a torque proportional to the'displacemcnt of said piston to said rotor to opposesaid rotor displacement, whereby said rotor is restrained em i a ae and e dis lase ti aid s gives a measure ithe-l qr nrodueed by, said rotor and hence a measure of the. rate. of turn of s aid platform.

7., Fire control apparatus comprising a free; gyroscope, a sight; means responsive to positional displacement between said sight and said gyroscope foncausing the spin axis of said gyroscopee r ki h a target mit-meensl e ntrelline a computing; mechanism from s gl-- gyro -.f r' cletermining gun aiming angles for engaging the target.

8. Stabilized gyroscopic tracking apparatus sen. nev o of said; rim and means or r cking said ine of igh ia tarsetleemn i ng means. for n A ueina e0. esn nd n to thelneeessa i az muth, and levati niate 0i han e o said 1 .1 Of i ht to, main ain said line, o ien d o.- fetd aid ar et. mean or roduc n r u respectively proportional to said elevation rate,- and. ra e i nals me n or convertin 3191. ra e. torque e a torqu orrespond- 18 1 rate heslant pla ee n ainina sa d ne of. si ht ansiimea si r applying said lev on ands antp ane azimuth torqu s. to re: peet v xes o ai yre o. cause. said, spin. axis to presses, whereby he o i n at on o a d 9 1 xi re ends heorientationof said. target; and e dterques orrespo d. sp iv ly to. the,

m th. ra e si nalv o, a i nal: rresp n ng to.

z muth ate. in he antp ane containin a d;

axis and perpendicular. to the vertical planecone tainingsaid axis, means, responsiveto said signals for producing. torquesrespectively. proportional. tp sa delevat en a and slantnlaneazimuth. rate. signals, means for, applying said, torques to. respective axes of said gyrotocausesaid spin,

axis. to precess, whereby the orientation of said,

spin axis correspondstorqrientation,of saidtarget, and said torques correspond respectively to the. azimuth and. elevation rates. of motion of, said;

target.

10. Stabilized gyroscopic tracking apparatus for tracking with. a. target comprising a. free gyro having a spin axis precessible .in elevation about, a horizontal axis perpendicular to said spin axis.

and in slant planeazimuth about an axis per-s pendicularv to bothsaid spin andhorizontal axes, means for producing a signal corresponding to the azimuth rateof said spin axis necessary to maintain said axis: oriented I toward said; target, I

means for producing atorque corresponding to said. azimuth rate signal, means for converting said azimuth rate torque to a torque corresponding to slant plane-azimuth rate, and means for;

applying said oonvertedtorque to said gyro about said horizontal axis toprecess said spin; a-xis slant-plane azimuth, whereby the orientationoi,- saidspin axis corresponds togthe orientation of;

said targetandsaid;signakcorresponds to the;

angular velocity Qfs'aid target: in azimuth.

11-; Stabilized fire controlapparatus comprising;- anorientable; radio sca ning device, radio means. or; u at al y pr ducin ;s e alscerrespende n a ore at v displacement:between'ithe. ori tae Q d-d nd h pr entat n f a e a .Q e m a n -.heri ntal e m al. axi and a s endsim al axisp rp ndieu t r to, m an propor nalo sa d ignals-r e: said ax s ate-cause:

ie pin x s-of aid gymto tra lswithrsaid tar et, an o low p m ans-mo t ol edby a daav a er nth and. el tion. ates of motion, of said; 

